Spinning flywheels have been used for centuries for jobs from making pottery to running steam engines. Now the ancient tool has been given a new job by a Massachusetts company: smooth out the electricity flow, and do it fast and clean.

Beacon Power’s flywheels — each weighing one ton, levitating in a sealed chamber and spinning up to 16,000 times per minute — will make the electric grid more efficient and green, the company says. It’s being given a chance to prove it: the U.S. Department of Energy has granted Beacon a $43 million conditional loan guarantee to construct a 20-megawatt flywheel plant in upstate New York.

“We are very excited about this technology and this company,” said Matt Rogers, a senior adviser to the Secretary of Energy. “It’s a lower (carbon dioxide) impact, much faster response for a growing market need, and so we get pretty excited about that.”